BIRMINGHAM, Alabama - The disappearance of a Hueytown woman in Panama City six years ago will be featured Monday night on Investigation Discovery's news series "Last Seen Alive."

Pamela Pendley Biggers, 52, has been missing since Jan. 27, 2008 when she and a coworker went to Panama City Beach on business.

Biggers suffered from mental health issues, possibly bipolar disorder and/or schizophrenia, but she refused to see a psychiatrist and didn't take her medication on the trip with her, according to missing persons' website The Charley Project.

Biggers and her coworker checked into the La Quinta Inn on Thomas Drive. She spoke with her husband, Don, by phone about 5:30 p.m. and, after dinner, went to her room at 7 p.m. She was discovered missing the following morning at 6 a.m.

It appeared Biggers had been reading in bed, but it didn't look like she slept in in there. There were pillows propped against the headboard, and an open book and Biggers' reading glasses were on the bed side table. There were no signs of a struggle.

No one reported seeing Biggers leave. All of her belongings – purse money, keys, identification, clothes, cell phone and car – were still at the motel.

Family members told police she had never before wandered off.

According to The Charley Project, Biggers had been acting strangely the day of her disappearance: she began hearing voices and appeared to be having conversations with people who weren't there. She was under stress because her son was about to be deployed to Afghanistan.

Monday's episode will air at 9 p.m. (CST). Biggers' husband will team up with missing-persons expert Monica Caison, who has experience searching for the mentally ill. Biggers' sister and coworker will join them as they all return to Panama City to conduct their own investigation and follow new leads to homeless shelters in Miami.Anyone with information on Biggers' disappearance is asked to call the Bay County Sheriff's Department at 850-747-4700.